The present invention relates generally to guns adapted to install conventional plastic rivets, such as expansion rivets and the like. More particularly, the present invention is directed to a hand held, semi-automatic air powered gun which serially ejects and installs expansion rivets.
Plastic expansion rivets are well known in the fastening arts. Preferably such rivets are molded through conventional plastic injection molding techniques in a one-piece unit. Typically, modern expansion rivets include an intermediate flange portion separating an integral, generally cylindrical stem from an adjacent cooperating tubular expansible segment. The latter segment is relieved radially, resulting in separate elongated sections which enable the segment to expand. Expansion or "blind" rivets fasten work pieces together when the expansible rivet portion is first inserted through the adjacent work piece orifice, and thereafter "expanded" by forcible axial insertion of the stem by force sufficient to break it away from and subsequently penetrate the flange. Expansion prevents subsequent withdrawal of the fitting, since the expanded shank compressably, frictionally occupies the void formally presented by the aligned work piece orifices. It is well known to apply such rivets with the use of hand-held tools such as mallets or the like.
Known prior art expansion rivets, which may be otherwise known as "blind" rivets, fasteners or the like, are seen in the following U.S. Pat. Nos.: 4,222,304; 2,030,169; 2,408,559; 2,803,984; 3,178,989; 3,230,818; 3,251,260; 3,294,303; 3,521,521; 3,702,088 and 3,758,241.
In the aircraft industry, for example, aligned body or structural members of aircraft often must be temporarily fastened together during certain assembly phases. In the prior art it is known to employ a "Clico" or "Wedgelock" metallic tool which includes an expansible metallic sleeve. The sleeve includes a number of fork-like tines which are expanded when a flat tongue is projected axially therewithin. While such a tool will yieldably maintain two or more apertured aligned work pieces together, the costs involved in employing a vast army of these tools is a major detriment. Rather than employ such a tool, metallic rivets can and have been used for temporary assembly purposes. However, they must be subsequently removed prior to completion of final assembly. During the critical removal stages, damage to high tolerance, metallic sheet metal parts may occur in response to drilling. Metal shavings and the like present an obstinate clean-up problem. Thus the employment of plastic expansion rivets for purposes such as this is desirable, as previously suggested in U.S. Pat. No. 4,493,205, owned by the same Assignee as this case.
It has thus been found desirable to provide some form of pneumatic rivet applicator tool for quickly and easily inserting plastic expansion rivets during the assembly of metallic elements, such as those employed in the aircraft industry.
However, as for example during the construction of aircraft wing sections, a great number of plastic expansion fittings must be sequentially installed. Such work is repetitive and time consuming, and even the benefits of a manual gun may not sufficiently reduce assembly time requirements where literally thousands and thousands of rivets must be installed. Hence we have designed a semi-automatic gun which serially outputs and installs expansion rivets without the need for constant manual single shot reloading. The closest prior art known to applicant is U.S. Pat. No. 4,364,506 which discloses a gun-like fastener installation tool.